N-heterocyclic carbene palladium complexes with different N-coordinated ligands: Comparison of their catalytic activities in Suzuki-Miyaura and Mizoroki-Heck reactions

Abstract

In this paper, we have reported the synthesis and catalytic activities of four new anthracene substituted imidazole-based palladium N-heterocyclic carbene complexes. The synthesized complexes, 2a-d, were stabilized with different N-heterocycles, namely pyridine, N-methylimidazole, N-vinylimidazole and 4,5-dimethylthiazole, respectively. The complexes were completely characterized using H-1 NMR, C-13 NMR, IR, LC-MS spectroscopic methods and elemental analyses. The crystal structures of 2a, 2c and 2d were also reported. The catalytic activities of all the complexes were tested for Suzuki-Miyaura and Mizoroki-Heck cross-coupling reactions in aqueous medium. According to the results, for the Suzuki-Miyaura reaction, the pyridine bearing complex 2a, and for the Mizoroki-Heck reaction, the 4,5-dimethylthiazole bearing complex 2d were found to be the most active catalysts. (C) 2019 Elsevier Ltd. All rights reserved.